Year one 17 inch ralleys

I like them on every E and B body I see. just don't know if I want to spend that much coin to find out they don't look right on a 69 dart

Forget looking right, they're not going to fit right. 17x8 and 4.5" of backspace will put you on the fenders on an A body. Maybe you could make it work with 225's and some negative camber, but it would be close. And if you're lowered it'd be even worse.